Free tool for home coffee roasters
Coffee blend calculator
Turn percentages into grams, then check the stock you have. No signup needed.
How to calculate a coffee blend
Multiply the batch weight by each percentage divided by 100. For a 300 g batch at 60/25/15, weigh 180 g, 75 g and 45 g. This calculator allocates any rounding remainder so whole grams still add up to your chosen batch.
Your 300 g batch
- Chocolate base: 180 g (60%)
- Caramel middle: 75 g (25%)
- Citrus accent: 45 g (15%)
Total: 300 g. Whole grams are allocated so the batch total stays exact.
For pre-roast blending, enter green weights. For post-roast blending, enter roasted weights. Keep both the batch and stock in the same weight basis.
Calculations stay in this page. To keep recipes with your inventory and roasting notes, create a Percolate account or adapt a Shelf recipe.
Green or roasted weights?
A pre-roast recipe combines green beans before roasting. A post-roast recipe combines separately roasted coffees by roasted weight. Roast weight loss varies, so the two sets of proportions are not interchangeable. Use stock measured on the same basis as your batch.
Planning a half-caff batch
A 300 g equal-weight blend uses 150 g regular beans and 150 g decaf beans. That describes the recipe’s bean weights, not measured caffeine. Decaf retains some caffeine, and regular coffees differ too.
Choose a starting recipe
Explore the Blend Shelf, including espresso and decaf recipes. Read the blending guide for ratio tests and substitutions, then record a small roasting trial.